1. Field of the Invention
This invention relates to a surgical trocar catheter for drainage. More particularly, this invention relates to a trocar for use with a drainage catheter where the trocar has a spring biased safety shield mechanism.
2. State of the Art
Trocar catheters for drainage are well known in the surgical arts. These devices generally include a flexible, partially elastic catheter and a metal trocar which is removably inserted into the catheter. One such known device is a chest drainage trocar catheter shown schematically in longitudinal cross section in prior art FIG. 1 The prior art chest drainage trocar catheter device 10 includes a flexible partially elastic catheter 12 which is approximately nine and one half inches long having a cross section of approximately one quarter of an inch and an inner diameter defining a lumen 13 of approximately one eighth of an inch. The lumen 13 has a stepped smaller diameter portion 16 at the distal end 14 of the catheter. The proximal end 18 of the catheter is flared for coupling with a drainage conduit or syringe (not shown). The distal end of the catheter preferably includes a plurality of openings or ports (not shown) for drainage. A metal trocar 20 approximately eleven inches long having an outer diameter of approximately one eighth of an inch is inserted into the lumen 13 of the catheter 12. The distal end of the trocar has a piercing point 22 and the proximal end of the trocar has a small circular gripping or pushing plastic base 24. The piercing point 22 of the trocar has a stepped smaller outer diameter 26 which mates with the stepped smaller inner diameter 16 of the distal end of the catheter so that the piercing point extends a predetermined fixed length beyond the distal end of the catheter. The trocar 20 is thereby prevented from passing beyond that point through the catheter. The stepped diameters of the trocar and catheter also insure that forward movement of the trocar 20 carries the catheter 12 with it.
In use, a sterile catheter with an inserted sterile trocar is removed from a sterile package, taking care that the catheter does not slip off the trocar. The surgeon grasps the proximal end of the catheter typically with four fingers wrapping around the catheter and thumb resting on the base of the trocar. The device is thrust into a patient's chest whereby the piercing point of the trocar incises the chest. The catheter, carried by the trocar, is forced through the incision into the chest cavity of the patient. After an appropriate length of the catheter has been inserted into the chest cavity, the trocar is removed from the catheter and a drainage conduit or device is coupled to the proximal end of the catheter in order to pull or drain fluids from the chest of the patient.
The prior art trocar catheter, as detailed in FIG. 1, has several disadvantages. First, the piercing point 22 of the trocar is exposed and can cause accidental pricks and punctures while the device is being handled prior to incision. Moreover, after the catheter is installed in the chest cavity and the trocar is removed from the catheter, the piercing point of the trocar is again exposed and presents the same dangers. Second, with the prior art device there is no effective means for preventing the catheter from sliding off the trocar when the device is being handled by the surgeon prior to incision. As both the trocar and the catheter must be sterile, the danger of the catheter detaching from the trocar before installation is that the catheter will fall onto a nonsterile surface and will be unusable.
Other known catheters include suprapubic catheters such as shown in FIG. 1a which is used with the a similar trocar as shown in FIG. 1, except that the trocar has a sharp beveled tip 222. The suprapubic catheter 212 is also a flexible partially elastic catheter having an inner diameter defining a lumen 213. The lumen 213 has a stepped smaller diameter portion 216 at the distal end 214 of the catheter. The proximal end 218 of the catheter is flared for coupling with a drainage conduit or syringe (not A metal trocar like the one shown in FIG. 1 is inserted shown). A metal trocar like the one shown in FIG. 1 is inserted into the lumen 213 of the catheter 212. The suprapubic catheter is also provided with a 5cc latex retention balloon 225 near its distal end 214 and a collar 223 for optional anchoring to the skin with sutures or tape after the catheter is inserted into the suprapubic region. Proximal of the collar 223, Y-ports 219 and 221 are provided for inflation and irrigation through luer connections 219a and 221a.
While the suprapubic catheter has many enhancements for use in the suprapubic region, it still relies on the same kind of trocar as the chest catheter of the prior art and suffers from the same disadvantages.